scholarly journals Water under Supercritical Conditions: Hydrogen Bonds, Polarity, and Vibrational Frequency Fluctuations from Ab Initio Simulations with a Dispersion Corrected Density Functional

ACS Omega ◽  
2018 ◽  
Vol 3 (3) ◽  
pp. 3453-3462 ◽  
Author(s):  
Anwesa Karmakar ◽  
Amalendu Chandra
Keyword(s):  
Hydrogen Bonds ◽  
Ab Initio ◽  
Vibrational Frequency ◽  
Density Functional ◽  
Supercritical Conditions ◽  
Ab Initio Simulations ◽  
Frequency Fluctuations

scholarly journals Recently synthesized (Ti1−xMox)2AlC (0 ≤ x ≤ 0.20) solid solutions: deciphering the structural, electronic, mechanical and thermodynamic properties via ab initio simulations

RSC Advances ◽  
2020 ◽  
Vol 10 (52) ◽  
pp. 31535-31546 ◽  
Author(s):  
M. A. Ali ◽  
S. H. Naqib
Keyword(s):  
Density Functional Theory ◽  
Thermodynamic Properties ◽  
Ab Initio ◽  
Solid Solutions ◽  
Density Functional ◽  
Functional Theory ◽  
Ab Initio Simulations

The structural, electronic, mechanical and thermodynamic properties of (Ti1−xMox)2AlC (0 ≤ x ≤ 0.20) were explored using density functional theory.

Ab initio HF and density-functional theory studies on the structure and vibrational frequency of huperzine A

1999 ◽  
Vol 488 (1-3) ◽  
pp. 21-28 ◽  
Author(s):  
Wei-Liang Zhu ◽  
Hua-Liang Jiang ◽  
Jian-De Gu ◽  
Jian-Zhong Chen ◽  
Jing-Kang Shen ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Vibrational Frequency ◽  
Density Functional ◽  
Huperzine A ◽  
Functional Theory ◽  
Ab Initio Hf

Exploring the deep interior of ice giants with shock-compression experiments and ab initio simulations: The case of metallic ammonia 

2021 ◽  
Author(s):  
Mandy Bethkenhagen ◽  
Jean-Alexis Hernandez ◽  
Alessandra Benuzzi-Mounaix ◽  
Frederic Datchi ◽  
Martin French ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Equation Of State ◽  
Ab Initio ◽  
Density Functional ◽  
Md Simulations ◽  
Physical Review ◽  
Gradual Transition ◽  
Chemical Physics ◽  
Ab Initio Simulations ◽  
Plasma State

<p>Ammonia is predicted to be one of the major components in the depths of the ice giant planets Uranus and Neptune. Their dynamics, evolution, and interior structure are insufficiently understood and models rely imperatively on data for equation of state and transport properties [1,2]. Despite its great significance, the experimentally accessed region of the ammonia phase diagram today is still very limited in pressure and temperature [3, 4].</p><p>We investigate the equation of state, the optical properties and the electrical conductivity of warm dense ammonia by combining laser-driven shock experiments and state-of-the-art density functional theory molecular dynamics (DFT-MD) simulations [5]. The equation of state is probed along the Hugoniot of liquid NH<sub>3 </sub>up to 350 GPa and 40000 K and in very good agreement with earlier DFT-MD results [6]. Our temperature measurements show a subtle slope change at 7000 K and 90 GPa, which coincides with the gradual transition from a liquid dominated by molecules to a plasma state in our new ab initio simulations. The reflectivity data furnish the first experimental evidence of electronic conduction in high pressure ammonia and are in excellent agreement with the reflectivity computed from atomistic simulations. Corresponding electrical conductivity values are found up to one order of magnitude higher than in water in the 100 GPa regime, with possible implications on the generation of magnetic dynamos in large icy planets’ interiors.</p><p> </p><p>[1] Scheibe, Nettelmann, Redmer, Astronomy & Astrophysics <strong>632</strong>, A70 (2019).</p><p>[2] Vazan & Helled, Astronomy & Astrophysics <strong>633</strong>, A50 (2020).</p><p>[3] Nellis, Hamilton, Holmes, Radousky, Ree, Mitchell, Nicol, Science <strong>240</strong>, 779 (1988).</p><p>[4] Radousky, Mitchell, Nellis, Journal of Chemical Physics <strong>93</strong>, 8235 (1990).</p><p>[5] Ravasio, Bethkenhagen, Hernandez, Benuzzi-Mounaix, Datchi, French, Guarguaglini, Lefevre, Ninet, Redmer, Vinci, Physical Review Letters <strong>126</strong>, 025003 (2021).</p><p>[6] Bethkenhagen, French, Redmer, Journal of Chemical Physics <strong>138</strong>, 234504 (2013).</p>

Ab initio simulation of the structure and dynamics of white phosphorus (P4) at low temperatures

1995 ◽  
Vol 73 (11-12) ◽  
pp. 710-717 ◽  
Author(s):  
P. Jeffrey Ungar ◽  
Kari Laasonen ◽  
Michael L. Klein
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Density Functional ◽  
Local Density ◽  
Orientational Order ◽  
Intermolecular Forces ◽  
White Phosphorus ◽  
Basis Set ◽  
Cell Parameters ◽  
Ab Initio Simulations

Ab initio simulations of low-temperature white phosphorus (β-P4) were performed using Car–Parrinello density-functional-theory molecular dynamics and a plane-wave basis set. Gradient corrections to the local density approximation were used to obtain a better description of the weak intermolecular forces. Starting with unit-cell parameters and atomic coordinates recently verified using neutron scattering, molecular dynamics trajectories over 9–10 ps were obtained for temperatures of 50 and 145 K. The computations show that the distortions from ideal tetrahedral P4 molecules found in the reduction of the neutron data may be a finite-temperature effect and not an artifact of the data analysis. Examination of the molecular reorientational dynamics shows that orientational order persists throughout the simulations, which suggests that β-P4 is an orientational crystal.

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